Vascular calcification (VC) has a high incidence in patients with chronic kidney disease, which is a worldwide public health problem and presents a heavy burden to society. Hypoxia-inducible factor (HIF)-1α, the active subunit of HIF-1, has been reported to play a vital role in high phosphate-induced VC. However, the underlying mechanism is still undetermined, and effective treatment is unavailable. In the present study, human aortic smooth muscle cells (HASMCs) were cultured under normal or high phosphate media conditions. HIF-1α small interfering RNA and overexpression plasmids were employed to regulate HIF-1α expression. Phosphonoformic acid was employed to restrain the function of type III sodium-dependent phosphate cotransporter 1 (Pit-1). The expression levels of HIF-1α, Pit-1, runt-related transcription factor 2 (Runx2), and smooth muscle 22 alpha (SM22α) were evaluated, and the calcium contents were also examined. Cell growth was assessed using an MTT assay. High phosphate stimulation caused an upregulation in HIF-1α and Pit-1 expression levels and induced calcium depositions in HASMCs. Upregulation of Runx2 expression accompanied by downregulation of SM22α expression was observed in the high phosphate group. Following the suppression of HIF-1α expression, there was a concomitant attenuation in Pit-1 expression, calcium deposition, the alteration of phenotypic transition marker genes, and vice versa. The most serious calcium deposition was noted in HASMCs cultured under high phosphate conditions which were pretreated with a HIF-1α overexpression plasmid. However, when the biological functions of Pit-1 were restrained, the putative serious calcium deposition was not formed even in HASMCs transfected with a HIF-1α overexpression plasmid. The findings confirmed that HIF-1α regulated Pit-1 expression and exerted its pro-calcifying effect through Pit-1, which identified HIF-1α and Pit-1 as therapeutic targets for high phosphate-induced VC.

中文翻译：

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缺氧诱导因子 1α 通过 III 型钠依赖性磷酸盐协同转运蛋白 1 调节高磷酸盐诱导的血管钙化

血管钙化（VC）在慢性肾脏病患者中发病率较高，是一个世界性的公共卫生问题，给社会带来沉重负担。据报道，缺氧诱导因子 (HIF)-1 α（HIF-1 的活性亚基）在高磷酸盐诱导的 VC 中发挥着至关重要的作用。然而，其潜在机制尚未确定，且尚无有效的治疗方法。在本研究中，人主动脉平滑肌细胞（HASMC）在正常或高磷酸盐培养基条件下培养。采用HIF-1α小干扰RNA和过表达质粒来调节HIF- 1α表达。膦甲酸用于抑制 III 型钠依赖性磷酸协同转运蛋白 1 (Pit-1) 的功能。评估HIF- 1α、Pit-1、runt相关转录因子2（Runx2）和平滑肌22α（SM22α ）的表达水平，并检查钙含量。使用MTT测定评估细胞生长。高磷酸盐刺激导致 HIF-1 α和 Pit-1 表达水平上调，并诱导 HASMC 中钙沉积。在高磷酸盐组中观察到 Runx2 表达上调，同时 SM22 α表达下调。 HIF- 1α表达受到抑制后，Pit-1表达、钙沉积、表型转变标记基因的改变随之减弱，反之亦然。在用 HIF-1 α过表达质粒预处理的高磷酸盐条件下培养的 HASMC 中发现最严重的钙沉积。然而，当Pit-1的生物学功能受到抑制时，即使在转染HIF-1α过表达质粒的HASMC中也不会形成假定的严重钙沉积。研究结果证实HIF-1α调节Pit-1表达并通过Pit-1发挥其促钙化作用，从而确定HIF-1α和Pit-1作为高磷酸盐诱导VC的治疗靶点。